Inventories (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Aluminum and steel coil	$ 72,587	$ 58,153
Raw materials	16,427	15,291
Work in process	2,467	1,936
Finished products	14,904	14,380
Inventories, net	106,385	89,760
Summary of Obsolete Inventory Reserve [Roll Forward]
Balance, beginning of year	2,441	2,911	3,009
Charges to costs and expenses	4,037	3,972	4,386
Write-offs	(3,883)	(4,487)	(4,534)
Foreign currency translation	(129)	45	50
Balance, end of year	$ 2,466	$ 2,441	$ 2,911